265 - Two Year Follow up of a Unique Minimally Invasive Lateral Lumbar Locki...

Oral Posters: Innovative Technologies

Presented by: M. Songer - View Audio/Video Presentation (Members Only)

Author(s):

M. Songer MD(1)

(1) Michigan State University, College of Human Medicine, Orthopedics, Marquette, MI, United States

Abstract

Introduction: Louis Pimenta MD helped popularize the MIS lateral approach to the lumbar spine. Surgical placement of the lateral lumbar cage is now common with supplemental fixation being either a lateral plate or backing up with pedicle screws. The lateral plate creates a significant lateral profile that may irritate the exiting nerve roots. The pedicle screws add significant time and cost to the operation. This is the first report of a unique locking bulb keel with integral fixation to the cage with zero profile outside of the vertebra.

Methods: The MIS lateral locking lumbar cage was implanted in 46 levels in 40 patients. Oswestry disability index and visual analog pain scores were prospectively collected pre-operatively, and at 6, 12, and 26 weeks as well as 1 and 2 years post-operatively. AP and lateral x-rays were obtained at each of these time periods. Flexion/extension lateral x-rays were obtained pre-operatively as well as 3 and 6 months post-operatively. If bridging bone across the disc space was not clearly visualized, then a CT scan was obtained at 6 months. A neurological exam was performed at each time interval. Student T-test statistical analysis of the results were obtained.

Results: The VAS score pre-operatively was 7.04 that dropped to 2.58, 1.54, 1.79, 0.9, and 1.93 at 6 weeks, 3 months, 6 months, 1 year, and 2 years respectively. This corresponds to a percentage drop of 63, 78, 75, 87, and 73 at each interval respectively, which was statistically significant. The ODI score pre-operatively was 46.62 dropping to 38.08, 25.43, 25.55, 17.83, and 28.15 at 6 weeks, 3 months, 6 months, 1 year, and 2 years respectively. This corresponds to a percentage drop of 22, 48, 47, 63, and 42 at each interval respectively, which was also statistically significant. All patients were fused at 6 months that were verified by x-ray or CT scan. There were no revisions for non-unions, hardware failure, or any devised related failures. There were no intra-operative complications, and no fractured vertebrae. One patient had some left quadricep weakness that resolved between 6 and 12 weeks. Two patients fell within the first 3 months and sustained compression fractures, but neither disrupted the index level. One of those patients had an adjacent level fused within 1 year. Both ended with excellent results. One patient had a DVT post-operatively that resolved with treatment. There were no post-operative infections. One 83 year-old man died before his 3 year follow-up unrelated to surgery. The mean operative blood loss was 121 ml. The average hospital stay was 2.08 days with 16 patients staying only one day.

Discussion: The lateral or anterolateral lumbar approach is ideal for radicular pain secondary to foramenal stenosis, adjacent level DJD, grade 1 degenerative spondylolisthesis, and degenerative scoliosis. This study concurs with other reports that show minimal blood loss with few complications and good outcomes in the hands of experienced surgeons. This new locking cage system creates a rigid construct in 3 planes: flexion/extension, torsion, and lateral bending.

Conclusion: This initial report demonstrates good clinical success with this new technology. However, the results should be supported by further clinical studies with more patients.